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5.7 max bore

41K views 49 replies 12 participants last post by  Hemihackman 
#1 ·
Guys need some help. I've got an 04 block that I was just doing a mild rebuild on. 6.1 cam and springs. Crower timing chain and 6.1 pump. I've been kicking back and forth on changing out the rotating assembly. I can across a deal on a full 6.1 assembly. My main concern is the max bore. I've read it should take 4" no problem but then other who claim to have gone 4.055 and ran the 6.1 rotating assembly in them. It's a CB block non mds. Does anyone have any experience in doing this? Block is going to the machine shop his weekend for cleaning and cam bearings. Might see if they can sonic test it as well.

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#3 ·
That's what I've read as well. I've read where someone used a few AC blocks as they were said to have thicker walls and he did 3 of those with 6.1 assemblies but haven't read anything on the CB blocks. Heard the early blocks were thicker but who knows


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#10 ·
No only upgrades is dynatech long tubes, 6.1 cam advanced either 4 or 6 degrees, intake and exhaust mods, 6.1 dampener and hypertech 93 tune. Will do a dyno tune down the road. It's going in an 04 durango


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#12 ·
Guys need some help. I've got an 04 block that I was just doing a mild rebuild on. 6.1 cam and springs. Crower timing chain and 6.1 pump. I've been kicking back and forth on changing out the rotating assembly. I can across a deal on a full 6.1 assembly. My main concern is the max bore. I've read it should take 4" no problem but then other who claim to have gone 4.055 and ran the 6.1 rotating assembly in them. It's a CB block non mds. Does anyone have any experience in doing this? Block is going to the machine shop his weekend for cleaning and cam bearings. Might see if they can sonic test it as well.

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Doesn't matter what year the pre Eagle 5.7 block is or if it's MDS or not, ,
most will go to 4.0 inch in over bore, sonic the block and go from there, core shift will affect how far you can go. I've gone as big as 4.08 with a 53021319AC block and 4.09 with an 53021319CB the 53021319AG I've gone as large as 4.03 with room to spare, but no rhyme or reason behind any of it, 53021319AC/AG/CB I have one of each that I wouldn't bore more than 4.0 , I have a pair of 6.1's that would not trust to bore out to 4.07 , sonic the block
 
#18 ·
If you bore the cylinders.....would you need a bigger opening on the headgasket?? It would make sense since the gasket lines up perfectly on a stock bore.

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#22 ·
Here's a thought.

If you bore out a 5.7.... to 0.040 over...that would make it a 3.96..... if you were to need bigger gaskets...at that point one could use 6.1 gaskets right?

6.1 is 4.06
5.7 is 3.92
Bored 3.96.


Making it .010 within the limit.


Or am I wrong? It should still seal the chamber correctly .....

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#24 ·
Yea... But I've researched with $85/piece price tags haha at the cheapest..

However, the gasket can't be too much bigger than the chamber...right?

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#26 ·
I agree.

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#28 · (Edited)
Now, can someone tell me what I just read??

It sounds like it's said to be "possible" to bore bigger than 4.00.

I'm starting to get confused.... [emoji53][emoji53][emoji53]



And now here.... This suggest the block was bored FROM something to the 4.055 that the 6.1 contains which is over 4.0. Normally, a statement contains the words, "has a bore of" or something similar.

Does that suggest the 6.1 is a bored out 5.7?



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#29 ·
Simple answer is yes, 4 to 4.03 is very doable for the pre Eagle blocks. Arrington will sell you a 410 CI based 5.7 Arrington 410 Short Block - shopHEMI.com , there are no off the shelf pistons for a 4 in bore 5.7 Hemi , you can use some brand X pistons but they need to be modified.
your best bet is Custom pistons from Mahle(SP) or Diamond .
as for a 4.055-4.08 (stock 6.1+) bore 5.7 block, if you find a block that the cores were spot on when it was casted , it's doable, most o3-04s can go 4.055/4.06 I've gone as large as 4.09, I would not do it again , that engine after a year had hots spots in the bore and sure as all he L L would of blown up if it was boosted
. sonic test any block before boring
 
#30 ·
Proof.... Got it.

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#31 ·
No one can tell you that your block will go that large. You have to get it sonic checked to see what it will accept. Not every block is the same. Getting it checked is not expensive at all ~$50.
Factory blocks are not perfect. There are core shifts in the manufacturing process. So while most of the cylinders will accept that size. One cylinder may be off center a little and cause a thin spot. Now the manufacturing process have come a long ways so these variances have tightened up a lot. Depending on your machine shop,and how bad the shift is, they can realign the cylinder to be centered but the "thin" spot will be as thick as it ever will be.
 
#32 ·
Understood. That makes quite a bit of sense.

I hope the OP is reading these.

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#33 · (Edited)
#34 ·
Any update on this. I'm curious to know.
 
#36 ·
But why would you bore it any further than a. 4.055 on a 5.7 block anyway ? That doesn't really make any sense.

Safe than sorry huh? Or should I say Stock and boring.

Take risks lol.

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#42 ·
I’ve been curious about this for a while. I have a set of 6.1 pistons and rods and got them cheap with low miles, would just need a crank. I have three spare 5.7 blocks sitting in my garage. Been contemplating this and seen that it hasn’t been done much in regards to this topic. Obviously it would sonic tested and I have awesome machine shop / engine builder. I was thinking of doing this with a set of ported eagles and 6.1 intake. Possibly using a .219/.223 cam and / or talking to Dave at MM to see what’s best for this. Kinda just throwing this around.

I would love to do a 5.7 392 with ported eagles but bored 5.7 is more cost effective for me. I could do this almost complete for what a 392 stroker cost. Unfortunately I don’t have all the $$$$ the other guys have on building a motor.
 
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